Link Building
Building inbound links to your website is an important part of any search engine strategy. My preference is via well edited directories, and through quality content which leads to people naturally linking to your website. Recently there are a number of websites which allow you to advertise on other sites via text links at a monthly fee. It has been known for search engines to frown upon this strategy and not count inbound links from certain sites. So be careful about this.
Two of the most popular sites for buying text links are
1. adbrite.com
2. text-link-ads.com
The better method is to exchange links with other high quality websites with relavant content to yours.